Hogster
Key Veteran
Location: Surrey, UK
My Posts This: Topic Forum | Hi all 
It's time for another of my build logs as I've just built a new panorama head for my Canon EOS 40D / 10-22mm lens combo. Sit back and enjoy! 
Soo, as with all my designs, I start with a pencil and paper:
I already had a pretty good idea in my mind of what the eventual head would look like, so the sketches were just a way of noting down the key dimensions. Fortunately the key dimensions for my camera/lens combination were already available www.panotools.info/mediawiki/index.php%3Ftitle%3DEntrancePupildb+entrance+pupil+database+canon+40d&hl=en&ct=clnk&cd=3&gl=uk]here[/url] so I didn't have to calculate the location of the lens' "entrance pupil" (why the original site isn't working I'm not sure ... I'm glad Google had a cache of it!).
With that done, I made a start on one of the trickiest parts of the build, the knobs. As with the previous head I designed, I wanted to make the knobs myself. I did this by using Polymorph plastic to create a mould of an already-existing knob, and then using car body filler to create duplicate knobs. The knob I selected came from an old audio amplifier I think (I found it in the 'KNOBS' box in our attic  ). So, first stage is to pour the Polymorph pellets into hot water:
When heated, they turn from white to transparent – once they're transparent you can start moulding with it. You have to knead the pellets first (like bread dough) to get rid of any air bubbles. Once that was done I pressed the existing knob into the plastic, and formed the plastic around the knob:
Once the Polymorph has cooled (which can be sped up by dunking the mould in cold water), it turns white again, and is INCREDIBLY tough!
With the mould finished, it was time to make the first knob. I need three in total for this head, two with M6 (6mm) threads, and one with a 1/4" BSW thread which will screw into the camera itself.
The knobs are made from P38 car-body filler which comes as a two-part mixture (the red stuff is the hardener):
One has to work quickly, as this stuff sets pretty fast! The filler was poured into the mould (which had now been greased with Vaseline to help the knob come out easily ...... blimey, one shouldn't read that out of context!   ), and I used a screwdriver to push the filler into all the corners of the mould.
About 10 minutes later I pulled on the bolt and the new knob came out ... Hmm, not terrific, but those holes can easily be filled with more P38:
20 minutes of filling, filing and sanding later ... much better!
The knob was then sprayed a few coats of grey primer and then a few coats of satin black paint (knob shown here during the priming stage):
The above steps were repeated until I had created a total of 3 knobs
Onto the structure of the head itself. I found this lovely piece of hardwood in my Dad's garage and it's perfect for this application! Really tight-grained and very hard. Here I have already marked out in pencil where it needs to be cut:
I use this mitre-saw for all the cutting - it ensures a perfectly perpendicular cut
Then the holes were drilled ...
... and ... hang on a minute! Tapping a thread into wood?!
Yup! I stumbled across this technique by accident a while ago ... if you tap a thread into wood and then soak the hole in thin CA:
... it forms a very hard plasticised thread! You just have to make sure the CA has tried before you test-fit the bolt ....
Next I rounded the corners using a belt sander:
Unlike the previous head I built, I wanted to have a separate knob for screwing the head to the camera. Unfortunately this would mean either having a large spacer between the two vertical parts of the head, or to chisel some of the wood away on each of the vertical parts .... hmm, picture = 1000 words
As you can see I chose the chiseling option, simply because I didn't use a long enough bolt when making the upper knob to allow a large spacer to be used! 
The problem with panorama heads, is that if you're using a large, heavy camera (with a heavy lens), friction alone (from tightening the upper knob) will not be enough to hold the head at the desired angle. To get around this, I devised this simple system, consisting of a large washer with holes drilled in it, CA'd to a stack of washers behind it, CA'd to one part of the head. On the other part, I sunk a small nail with a flattened end:
You can probably see how it works I decided on the spacing of the holes by experimenting to see how much I needed to rotate the camera between each row of photos.
Not much left to do now. This is the bottom part of the head, and I'm using three 1 1/4" brass screws to hold the two parts of the head together ... definitely don't want those coming apart!
To add a final extra bit of strength, I CA'd a 45° wedge between the two main parts of the head:
With that complete, I could start with the painting!
Again I gave the parts a few coats of grey primer, and then finished it off with satin black.
Whilst painting I realised I hadn't quite finished building yet! I needed to make the spacer that sits underneath the head, which connects the head to the tripod. This is simply made from two discs of wood (the same wood the head is made from) which are CA'd together, with a different thread tapped into each one:
In one half is an M6 thread, and in the other is a 1/4" BSW thread (which the tripod screws into).
With that done, the building was *finally* complete, and I just had to finish the painting
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) plywood, 30mm across. Lots of cutting and sanding later:
